Bug: tessellation shaders not loading when separate files

Author: einarf

demosys/loaders/program/separate.py

@@ -17,8 +17,8 @@ def load(self):
             vs_source,
             geometry_source=geo_source,
             fragment_source=fs_source,
-            tess_control_shader=tc_source,
-            tess_evaluation_shader=te_source,
+            tess_control_source=tc_source,
+            tess_evaluation_source=te_source,
         )
         prog = shaders.create()
 

demosys/opengl/program.py

@@ -70,7 +70,7 @@ def from_single(cls, meta: ProgramDescription, source: str):
 
     @classmethod
     def from_separate(cls, meta: ProgramDescription, vertex_source, geometry_source=None, fragment_source=None,
-                      tess_control_shader=None, tess_evaluation_shader=None):
+                      tess_control_source=None, tess_evaluation_source=None):
         """Initialize multiple shader strings"""
         instance = cls(meta)
         instance.vertex_source = ShaderSource(
@@ -93,6 +93,20 @@ def from_separate(cls, meta: ProgramDescription, vertex_source, geometry_source=
                 fragment_source,
             )
 
+        if tess_control_source:
+            instance.tess_control_source = ShaderSource(
+                TESS_CONTROL_SHADER,
+                meta.path or meta.tess_control_shader,
+                tess_control_source,
+            )
+
+        if tess_evaluation_source:
+            instance.tess_evaluation_source = ShaderSource(
+                TESS_EVALUATION_SHADER,
+                meta.path or meta.tess_control_shader,
+                tess_evaluation_source,
+            )
+
         return instance
 
     def create(self):

examples/terrain/dependencies.py

@@ -3,6 +3,16 @@
 effect_packages = []
 
 resources = [
-    ProgramDescription(label="terrain", path="terrain/terrain.glsl"),
+    # Program in one single file
+    # ProgramDescription(label="terrain", path="terrain/terrain.glsl"),
+
+    # Program split into separate shader files
+    ProgramDescription(
+        label="terrain",
+        vertex_shader="terrain/terrain_vs.glsl",
+        tess_control_shader="terrain/terrain_tc.glsl",
+        tess_evaluation_shader="terrain/terrain_te.glsl",
+        fragment_shader="terrain/terrain_fs.glsl",
+    ),
     TextureDescription(label="heightmap", path="terrain/Ridges_01_DISP.jpg"),
 ]

examples/terrain/resources/programs/terrain/terrain_fs.glsl

@@ -0,0 +1,10 @@
+#version 410
+
+out vec4 fragColor;
+in vec2 ts_uv;
+uniform sampler2D heightmap;
+
+void main() {
+    float color = texture(heightmap, ts_uv).r;
+    fragColor = vec4(color);
+}

examples/terrain/resources/programs/terrain/terrain_tc.glsl

@@ -0,0 +1,22 @@
+#version 410
+
+layout(vertices = 3) out;
+
+in vec3 v_position[];
+out vec3 tc_position[];
+
+uniform float TessLevelInner;
+uniform float TessLevelOuter;
+
+void main() {
+    tc_position[gl_InvocationID] = v_position[gl_InvocationID];
+    if (gl_InvocationID == 0) {
+        // Resolution inside the triangle
+        gl_TessLevelInner[0] = TessLevelInner;
+        
+        // How many segments each edge of the triagle should be split into
+        gl_TessLevelOuter[0] = TessLevelOuter;
+        gl_TessLevelOuter[1] = TessLevelOuter;
+        gl_TessLevelOuter[2] = TessLevelOuter;
+    }
+}

examples/terrain/resources/programs/terrain/terrain_te.glsl

@@ -0,0 +1,29 @@
+#version 410
+
+layout(triangles, equal_spacing, ccw) in;
+
+in vec3 tc_position[];
+out vec2 ts_uv;
+
+uniform mat4 m_mv;
+uniform mat4 m_proj;
+uniform sampler2D heightmap;
+
+void main() {
+    // gl_TessCoord is barycentric coordinates inside the triangle representing the new vertex positions
+    // We multiply that with the three vertex position to get the new vertex position
+    vec3 p0 = gl_TessCoord.x * tc_position[0];
+    vec3 p1 = gl_TessCoord.y * tc_position[1];
+    vec3 p2 = gl_TessCoord.z * tc_position[2];
+
+    // Add them together to get the actual world posision
+    vec3 pos = p0 + p1 + p2;
+
+    // Read the height from the heightmap
+    vec2 uv = vec2(0.5, 0.5) + vec2(pos.xz) / 400.0;
+    float height = texture(heightmap, uv).r;
+
+    // Emit new vertex
+    gl_Position = m_proj * m_mv * vec4(vec3(pos.x, height * 25.0, pos.z), 1.0);
+    ts_uv = uv;
+}

examples/terrain/resources/programs/terrain/terrain_vs.glsl

@@ -0,0 +1,8 @@
+#version 410
+
+in vec3 in_position;
+out vec3 v_position;
+
+void main() {
+    v_position = in_position.xyz;
+}